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please try to attend
Science Lecture Series 2014, Otterbein UniversityDr. Robert Grubbs, 2005 Nobel Laureate in Chemistry Professor of Chemistry, California Institute of Technology-General Lecture (Thursday, 2/20/14, 4 p.m., Riley Auditorium in Battelle Fine Arts Center): "Green Chemistry: Lessons from Catalysis"-The general lecture will be followed by a reception in the Science Building atrium.  Both events are free and open to the public.  -Technical Lecture (Friday, 2/21/14, 11:45 a.m., Roush 114):"Design and Applications of Selective Olefin Metathesis Catalysts"Please Try to Attend!
seasons debriefing
Seasons Debriefing
  • If the Northern Hemisphere were tilted 90 degrees towards the Sun, which location would be warmer in the summer: the Arctic Circle or Florida?
strange motion of the planets
“Strange” motion of the Planets

Planets usually move from W to E relative to the stars, but sometimes strangely turn around in a loop, the so called retrograde motion

what can we conclude from observing patterns in the sky
What can we conclude from observing patterns in the sky?
  • Earth OR Celestial Sphere rotates
  • Earth rotates around the Sun OR Sun moves about Earth
  • Moon rotates around the Earth or v.v.?
    • Must be former, due to moon phases observed!
  • Size of the earth from two observers at different locations
  • Size of moon & moon’s orbit from eclipses
simple observations profound questions
Simple observations – profound Questions
  • Just using eyes & brain can provoke “cosmological” questions:
    • Is the Earth the center of the Universe?
    • How far away are Sun and Moon?
    • How big are they?
    • How big is the Earth?
    • How heavy is the Earth?
earth or sun the center
Earth or Sun the Center?
  • Aristotle (384–322 BC)
    • Argued that the planets move on spheres around the Earth (“geocentric” model)
    • Argues that the earth is spherical based on the shape of its shadow on the moon during lunar eclipses
  • Aristarchus (310–230 BC)
    • Attempts to measure relative distance and sizes of sun and moon
    • Proposes, nearly 2000 years before Copernicus, that all planets orbit the Sun, including the Earth (“heliocentric” model)
counter argument or not
Counter Argument or not?
  • Objection to Aristarchus’s model: parallax of stars is not observed (back then)
  • Aristarchus argued that this means the stars must be very far away
measuring the size of the earth
Measuring the Size of the Earth
  • Eratosthenes (ca. 276 BC)
    • Measures the radius of the earth to about 20%
documentation discerns subtle effects
Documentation discerns subtle Effects

Hipparchus (~190 BC)

  • His star catalog a standard reference for sixteen centuries!
  • Introduces coordinates for the celestial sphere
  • Also discovers precession of the equinoxes
how far away is the moon
How far away is the Moon?
  • The Greeks used a special configuration of Earth, Moon and Sun (link) in a lunar eclipse
  • Can measure EF in units of Moon’s diameter, then use geometry and same angular size of Earth and Moon to determine Earth-Moon distance
that means we can size it up
That means we can size it up!
  • We can then take distance (384,000 km) and angular size (1/2 degree) to get the Moon’s size
  • D = 0.5/360*2π*384,000km = 3,350 km
how far away is the sun
How far away is the Sun?
  • This is much harder to measure!
  • The Greeks came up with a lower limit, showing that the Sun is much further away than the Moon
  • Consequence: it is much bigger than the Moon
  • We know from eclipses: if the Sun is X times bigger, it must be X times farther away